CORE SUMMARY ? CHEMICAL MIXTURES CORE Superfund sites contain mixtures of many contaminants. The US EPA Supplemental Guidance for Conducting Health Risk Assessments of Chemicals stated that ?approaches based on whole mixtures are preferred to component approaches?. The research community needs robust, analyte-rich methods suitable for complex matrixes. The scientific community needs new, specialized, more sensitive methods to separate, detect, and quantify dozens of polycyclic aromatic hydrocarbons (PAHs) and substituted PAHs with widely varying concentrations and chemical properties in complex, heterogeneous matrices. These challenges continue to drive the development of analytical methods for PAHs, substituted PAHs and PAH transformation products, as well as Superfund co-contaminants. It is demanding to analyze PAHs and x-PAHs in environmental and biological matrices because the samples are complex, the numerous isomers of alkylated and high-molecular- mass compounds are often difficult to differentiate, and we often lack standards and suitable reference materials. The primary goal of the Chemistry Mixtures Core (CMC) is to support other Superfund Center projects and cores. We will maximize their access to quality-assured quantitative analytical technologies and empower them to increase their creativity and knowledge. We will create new and improved methods for PAHs, PAH metabolites, and substituted PAHs (e.g., alkyl-, oxygen- and nitrogen- substituted PAHs). We will collaborate with the Data Management and Analysis Core (DMAC) to improve our unique web-based interface for requesting standards, certified reference materials and submitting samples. We will develop and improve our high-volume data production and management platform. We will expand the 1,530-analyte screen by continuing to develop reductionist methods for mixture analysis. We will create bioavailable real-world reference materials from Superfund soil, sediment and water extracts in collaboration with the environmental projects and provide these materials to the biological projects. We will provide web-based training material for analytical methods and bio-analytical technologies to center investigators and trainees.